Why not seek out Xiao Shiqing?
It's simply because he seems unreliable.
It's just a difference between falling from one pit of fire into another; why should I seek him out?
Comparatively, the Xiao Mansion is not as safe as the Pei Mansion.
In the Pei Mansion, as long as she stays obedient and performs well, she not only can get promoted but also sees hope in being freed from her slave status in the future.
But what about the Xiao Mansion?
Leaving aside the protagonist's fate in the original story, just look at her current plight.
She hasn't even gotten involved with Xiao Shiqing yet, and she's already facing assassination attempts. If she truly went to the Xiao Mansion, she wouldn't know when her life would end.
No matter how cautious one is, it's hard to guard against intentional harm; isn't the saying 'not afraid of thieves stealing, but afraid of thieves thinking of you' just this principle?